<template>
  <div id="app">
    <div>
      <p>请选择你要购买的书籍</p>
      <ul>
        <li v-for="(item,index) in arr" :key="index">{{item.name}}<button @click="buy(index)">买书</button></li>
      </ul>
      <table border="1" width="500" cellspacing="0">
        <tr>
          <th>序号</th>
          <th>书名</th>
          <th>单价</th>
          <th>数量</th>
          <th>合计</th>
        </tr>

        <tr v-for="(item,index) in arr" :key="index">
          <td>{{index + 1}}</td>
          <td>{{item.name}}</td>
          <td>{{item.price}}</td>
          <td>{{item.count}}</td>
          <td>{{item.price * item.count}}</td>
        </tr>
      </table>
      <p>总价格为:{{totalPrice}} </p>
    </div>
  </div>
</template>

<script>
export default {
  name: 'App',
 data(){
  return{
    arr: [
        {
          name: "水浒传",
          price: 107,
          count: 0,
        },
        {
          name: "西游记",
          price: 192,
          count: 0,
        },
        {
          name: "三国演义",
          price: 219,
          count: 0,
        },
        {
          name: "红楼梦",
          price: 178,
          count: 0,
        },
      ],
  }
 },
 methods:{
  buy(id){
    this.arr[id].count++
  },
 },
 computed:{
  totalPrice(){
   return  this.arr.reduce((prev,item)=>prev + item.count * item.price,0)
  }
 }
}
</script>

<style scoped></style>
